1. Field of the Invention
The present invention relates generally to simple, permanent magnets and, more particularly, to simple, permanent magnets having an increased magnetic force.
2. Related Art
There is considerable use for simple, permanent magnets of the horseshoe and bar magnet varieties. Common uses include simple paper anchors on refrigerators, field modifiers for more complex magnet systems, the retrieval of iron and other magnetic objects, location indicators for surgical implements, and machine shop anchors and dogs. Generally, these magnets are very limited in the strength of the magnetic field that they can generate.
Examples of permanent magnets having a relatively high field strength but that extends within an interior cavity of the magnet include permanent magnets configured in the form of a magic sphere or a magic cylinder. U.S. Pat. No. 5,216,401 describes each of these permanent magnet structures.
One way to further increase the field strength located within an interior cavity of a magic sphere or magic cylinder type of a permanent magnet, is to employ a magnetic insert. U.S. Pat. Nos. 5,382,936, 5,428,334 and 5,428,335, each of which are incorporated by reference herein, describe a permanent magnet assembly comprising a cylindrical or spherical shell of magnetic material having a hollow central cavity. The shell is permanently magnetized to produce a magnetic field within the central cavity and a magnetic insert is disposed in the central cavity to enhance the magnetic field therein.